Bar Code Glossary

The following is an extensive list of terms dealing with bar code technology.

AIAG: Automotive Industry Action Group; a standards body composed of representatives from American Motors, Chrysler Corporation, Ford Motor Company, General Motors, and Volkswagen of America, responsible for the development of a common automotive industry standard relating to bar code symbology and common format.
AIM: Automatic Identification Manufacturers; The trade association representing most major automatic ID manufacturers. AIM also publishes standards relating to many types of bar codes.
ANSI: American National Standards Institute; A private, nonprofit organization operating in the public interest to coordinate U.S. standards.
aspect ratio: The ratio of height to width of a bar code symbol. A code twice as high as it is wide has an aspect ration of 2; a code twice as wide as it is high has an aspect ratio of 0.5.
autodiscrimination: A feature of certain bar code readers which can automatically distinguish between various bar code symbologies and decode them.
automatic data collection: Automatic data collection includes any system or device for inputting information into a computer system without a human acting as an intermediary between the source of the data and the input device. This includes bar code, OCR, RFID, etc. See also automatic identification.
automatic identification: Automatic identification and automatic data collection encompasses a wide range of technologies which have as their purpose automating the data entry process. These technologies include bar code, optical character recognition, magnetic stripe and magnetic ink character recognition (MICR), voice, RF identification, touch screens, light pens, hand print tablets, optical mark readers, and smart cards. Strictly speaking, automatic identification only includes those technologies that electronically detect a unique characteristic or unique data string associated with a physical object. The information obtained is used to classify the object through the use of electronic data processing (e.g. serial number, part number, color, manufacturer, etc.). See also automatic data collection.
bar code/barcode: An array of bars and spaces that are arranged in a predetermined pattern following unambiguous rules to represent elements of data that are referred to as characters. This term also is applied to 2 dimensional symbologies that are made up of dots and spaces.
bar code label: A label that carries a bar code and, optionally, other human-readable information; it can be affixed to an article.
bar code reader: A device used to identify and decode a bar code symbol.
bar code symbol: A graphic code, either printed or photographically reproduced, composed of parallel bars and spaces of various widths (linear bar code) or dots and spaces arranged in an array (2 dimensional bar code). A linear bar code symbol contains a leading quiet zone, a start character, one or more data characters (including in some cases a check character), a stop character, and a trailing quiet zone.
bar code symbology: A barcode symbology is a class of bar code. For example, Code 39 is a symbology as is UPC. There are more than 300 different barcode symbologies. Each requires different decoding software. However, many modern barcode readers can automatically identify which barcode symbology is being read and switch to the proper decoding program.
bidirectional: The ability to read data successfully, whether the scanning motion is from right to left or left to right.
bidirectional bar code symbol: A bar code symbol that permits reading left to right or right to left. Most common bar code symbols are bidirectional
binary code: A code that makes use of two distinct characters, usually 0 and 1.
bpi: Bits per inch. A measure of the density of data storage in bar code.
CCD: CCD stands for Charge Coupled Device, a semiconductor that has a plurality of light sensitive areas. A CCD can have a single linear set of light sensitive areas or the areas can be arranged in a 2-dimentional array. The device is used in a wide range of products, including video cameras and bar code readers.
CCD Scanner: A bar code reader that uses a CCD to pick up the image of a bar code. These scanners can read bar code without contacting the symbol like a laser scanner, but they cannot usually read the symbol at distances greater than 4 inches. They are prices between contact scanners and laser scanners.
Check character/checksum/check digit: A character included within a symbol whose value is based, mathematically, on other characters within the data string. It is used to perform a mathematical check to ensure the data is accurately read. see also modulo check character.
Codabar: A bar code format in which four bars and three spaces are used to represent the digits 0 through 9 and certain special characters. The code is characterized by four unique start/stop codes, variable intercharacter spacing, and code density of up to 10 characters per inch.
Code 2 of 5: The Two of Five code symbology encodes all information in the width of the bars. None of the information is carried by the spaces. Bars may be wide or narrow, and the wide bars are usually 3 times the width of the narrow bars. Spaces can be any width but are usually the same width as the narrow bars. See also Interleaved 2 of 5
Code 11: A code developed by Intermec that encodes 11 different characters (0 through 9 and '-'). Each character has three bars and two intervening spaces, for a total of five elements. Of these five elements, two are wide and three are narrow, except for the 0, 9, and '-' characters, which only have one wide element and four narrow elements. Normal bar code density is 15 characters per inch.
Code 16K: Code 16K is a multi-row code. Each symbol can have between 2 and 16 rows or stacks. Each row consists of a leading quiet zone, a starting pattern in UPC-A which specifies the row number, a 1 unit X dimension separator bar, 5 data characters encoded in Code 128 with the first character of the first word defining the number of rows in the symbol and the last two characters of the last word defined as check characters, a stop pattern in UPC-A which specifies the row number, and a trailing quiet zone. Each row is separated by a 1 module separator bar, and consists of 18 bars and 17 spaces. See also Code 49.
Code 39: A code developed by Intermec that encodes 43 data characters (0 through 9, A through Z, six symbols, and a space); three of the nine elements are wide and six elements are narrow. Normal bar code density is 9.4 characters per inch, depending on the 'X' dimension width. Also known as Code 3 of 9.
Code 49: Code 49 can pack in a lot of information in a very small symbol. The code accomplishes this by using a new approach. The code is a multi-row code. Each symbol can have between 2 and 8 rows. Each row consists of a leading quiet zone, a starting pattern, 4 data words encoding 8 characters with the last character a row check character, a stop pattern, and a trailing quiet zone. Each row is separated by a 1 module separator bar, and consists of 18 bars and 17 spaces. See also Code 16K.
Code 93: A code developed by Intermec that includes a character set that is identical to Code 39. Each character is constructed from nine modules arranged into three bars with adjacent spaces. Nominal bar code density is 13.9 characters per inch.
Code 128: A code developed by Computer Identics that encodes the full ASCII character set of 128 characters. Each character is represented by 11 modules and four bar widths.
contact reader/contact scanner/ contact wand: A bar code reader which requires physical contact between the code medium and the scanner. Contact readers are usually shaped like a pen. The tip is touched to the barcode and the reader is manually moved across the barcode by the operator.
continuous code: A bar code in which the space between two characters is part of the code. See also discrete code.
contrast/contrast ratio: Amount of difference in reflectance between a dark area or bar and a light area or space of a barcode symbol.
decoder: The electronic package that receives the signals from the scanner, performs the algorithm to interpret the signals into meaningful data, and provides the interface to other devices.
depth of field/depth of focus: The distance through which an optical system can maintain focus. The depth of field increases as aperture decreases.
discrete code: A bar code symbol in which the spacing between characters is not part of the code, and can vary within wide tolerances. See also continuous code.
direct thermal printer: See thermal printer.
DUN-13: See EAN-13.
EAN: European Article Numbering, now also called IAN (International Article Numbering),is the international standard bar code for retail food packages corresponding to the Universal Product Code (UPC) in the United States.
EAN-13: EAN-13 is one of two versions of the European Article Numbering system (EAN) and is a superset of UPC. EAN-13 has the same number of bar as UPC version A, but encodes a 13th digit. The 12th and 13th digit define the country code. The codes 00-04 and 06-09 are assigned to the United States.
edge error/edge roughness: Irregularities in the average or nominal edge of a bar code element due to printing. Large edge error can cause a symbol not to read.
film master: A precise negative or positive film transparency of a specific bar code symbol from which a printing plate is produced.
first read rate: The percentage of successful reads the first time a bar code is scanned.
FIM: FIM stands for Facing Identification Mark and is used on courtesy reply mail to identify the front of the envelope during presorting (Version A) or bulk mail (Version C).
fixed beam reader/scanner: A bar code reader that uses a stationary beam, usually laser, and relies on the relative movement of the item to be read as it passes the reader. See moving beam reader.
font: A family or assortment of characters of a given size and style of type. Bar codes can be printed using Bar Code True Type Fonts
hand-held reader/scanner: A reader held and operated by a human, thus enabling the reader to be brought to the symbol. These can be contact readers, or non-contact readers such as CCD and laser scanners.
helium-neon laser/ HE-NE laser: The type of laser which uses a glass tube filled with a mixture of helium and neon. This type of laser use to be used in many non-contact bar code readers. However laser diodes have replace this as a light source in bar code scanners.
HHDT: See PDT.
HIBC: Health Industry Bar Code. The format and symbology for automated data entry within the health industry.
human-readable: Referring to the representation of data in a form that can be read and understood by a human. The human-readable part of a barcode is the part that is printed in letters and numbers usually under the bar code.
IAN: International Article Numbering. See EAN.
ILD: Infrared Laser Diode. A semiconductor laser which produces light below 780 nanometers in the infrared spectrum.
infrared/infra-red: The band of light wavelengths too long for response by a human eye. This band is represented by waves between 750 and 4 million nanometers.
Interleaved 2 Of 5 Code/ I 2 of 5: A Code that encodes the ten digits 0 through 9. The name Interleaved 2 of 5 is derived from the method used to encode two characters. In the symbol, two characters are paired, using bars to represent the first character and the interleaved spaces to represent the second character. Each character has two wide elements and three narrow elements. It can achieve a density of 17.8 characters per inch.
ISO: International Organization for Standards, Central Secretariat, 1, rue de Varembe, CH-1211 Geneva 20 Switzerland. It is a nongovernmental organization and it helps set international standards for all fields.
JAN: Japanese Article Numbering. It is the same as EAN. See EAN.
laser: An acronym for Light Amplification by the Stimulated Emission of Radiation. A coherent, monochromatic light source.
laser diode: A laser made from a semiconductor material, and powered by applying an electrical potential to the material. These are used in all laser bar code scanners today.
laser marking: Etching of data by medium to high powered lasers directly onto marking surfaces such as metal, wood, and fiberboard. The material can also be designed as a laminate in which the top black layer is burned away to reveal a white layer.
laser printer: A laser printer uses the same printing technology used an office copier, except a beam of laser light under computer control is moved to draw an image on a charged photosensitive drum or belt. Where the light hits, the charge is destroyed. Small carbon particles called toner are applied to the drum or belt, and they stick to the areas that still are charged. This toner image is then transferred to paper and fused to the paper by heat or pressure.
laser scanner: An optical bar code reading device using a low energy laser as its source of light.
light pen: a pen-like, contact reader that is hand-held, typically employing an infrared or normal source of light. See wand reader, contact reader.
line separator: See row separator.
linear barcode: A barcode that encodes data only in one dimension. Data is encoded in the widths of the bars and spaces and no data is encoded in the lengths of the bars. The UPC or EAN barcode symbol found on many retail products is a linear barcode.
LOGMARS: The acronym for the Department of Defense project on LOGistics application of automated Marking And Reading Symbols. The LOGMARS project master plan was approved in June 1977, and its final report was issued on September 1, 1981 and adopted by the Department of Defense on September 29, 1981. It is a standard used throughout the Federal government for marking supplies. It is based on Code 39.
machine-readable: That characteristic of printed information that permits the direct transfer of information from a printed surface to a data processing system, without operator intervention.
mil: One thousandth of an inch (.001 inch), or .0254 millimeter. Bar code bar widths are commonly referred to as being a certain number of mils wide.
module width encoding: A method of bar encoding in which narrow elements represent binary zeros and wide elements represent binary ones.
modulo check character/digit: A specific character included in some bar code symbols that is generated from mathematical computation and the weighting of various characters in the symbol. The use of modulo checking increases the reliability that the bar code will be properly read by signaling the scanner if the modulo digit does not match what is expected given the remainder of the data.
moving beam bar code reader/scanner: A bar code reader that automatically sweeps a beam of light across a field of view and read the bar code within the field of view.
MRP: Material requirements planning
MRP II: Manufacturing resource planning
Multi-drop: See RS-485.
nanometer: A unit of measure to define the wavelength and color of light equal to 10 to the minus 9 meters. One nanometer is equivalent to 10 angstroms. The abbreviation for nanometer is nm.
non-contact reader/scanner: A bar code reader typified by fixed or moving beam scanners which can scan and decoded a bar code symbol without making contact with the symbol.
OCR-A: OCR-A (ANSI X3.17-81) is a character set designed for optimum readability for both machine and human. The character set contains 96 printing characters plus the character space, and includes digits, letters, small letters, and special symbols. Two editing symbols, character erase and group erase, are also included.
OCR-B: Character Set for Optical Character Recognition of OCR-B (ANSI X3.49-75) is an alternate character set to OCR-A and is easier for people to read. The character set includes 10 digits, upper and lower case letters, 33 punctuation marks and special characters (pound, dollar and yen symbols, for example).
omni-directional: Refers to the characteristic of some bar code formats to be able to be read regardless of orientation, or to the characteristics of some readers to read a bar code regardless of the bar code's orientation to the reader.
open system: Any barcode system that is designed to have the barcode labels read by scanners outside the control of the company printing the barcode label. Because the label will be scanned by barcode readers of unknown quality, the specification for the barcode label will be tighter in an open system.
passive reader: See video reader, CCD Scanner
PDF417: PDF417 is a Stacked or 2-dimensional bar code first proposed by Symbol Technologies in 1989. It is different from earlier bar codes (as well as other stacked bar codes) in several ways. The code allows stitching of partial scans, provides both error detection and correction, and provides a security versus density trade-off.
Plessey Code: Plessey Code and its variants (MSI Code, Telxon Code, and Anker Code) are pulse width modulated codes. It has seen wide use for shelf markings in grocery stores. See the code specification on BarCode 1.
PLU: Price Look Up. The process by which a bar coded item number is decoded, its price is looked up in a data base, and the price information is sent back to the scanning source.
PDT/PDET: A microprocessor-based, hand-held terminal capable of recording data by taking the terminal to the data source rather than bringing the data source to the terminal. PDETs can be either batch orientated, where the data is captured remotely and later transmitted to a computer, or an on-line device which immediately transmits the information to the computer.
Postnet code: The Postnet code was developed by the U.S. Postal Service to assist in automation of mail sorting. It can be found at the lower right on many letters which have been through regional postal facilities or on business reply envelopes.
Preprinted bar code/symbol: A symbol that is printed directly on a label or directly on an article by a company that specializes in bar code printing.
Quiet zone: The blank area immediately preceding the start character and following the stop character.
QWERTY: Refers to the standard data entry keyboard. Term comes from the first six letters at the upper left of the keyboard.
Reader: A reader is a device used for automatically reading data. The data can be stored in a bar code, alphanumeric characters, or electronically stored on a magnetic stripe or in the memory of a smart card. Typically a reader consists of a scanner or reading head, a decoder, and a data communications interface.
RF/ID: RF/ID uses small radio transponders which are activated by a reading transmitter. The transponder can carry a unique ID code or other information in its memory.
Row Separator: A line found in some 2D barcodes (usually a stacked barcode like Code 49) to help identify where one row of data ends and a new row begins. Some matrix barcodes also can have separators to identify where one block of data ends and a new block of data begins (for example, Data Matrix.)
RS-232C: RS-232C defines a data interface between a piece of data terminal equipment (DTE) and a piece of Data Communication Equipment (DCE). The specification limits the interconnection distance to 50 feet. The standard establishes the voltages and functions of signals on a 25 pin connector.
RS-422: This standard specifies voltages and impedance levels on balanced line interconnections. The data is transmitted on a twisted pair of wires (4 wires on a full duplex system). The system uses the difference of potential between the wire pairs rather that the potential with respect to ground as an RS-232C system does.
RS-485: RS-485 defines a system for interconnecting several data terminals to a common twisted pair balanced line. The interconnection is similar to RS-422, but all of the connected devices listen with their transmitters off. The host transmits a signal which addresses one of the devices. The addressed device turns on its data transmitter and transmits its data or response.
SKU: Stock Keeping Unit. An item at a particular geographic location.
Self-checking bar code: A bar code that uses a checking algorithm which can be applied against each character such that substitution errors can only occur if two or more independent printing defects appear within a single character. See also modulo check character.
Skew: rotational deviation from correct horizontal and vertical orientation; may be applied to a single character, line, or entire encoded symbol.
Source marking: The bar coding of a specific item at the point of initial production of the item; often refers to the inclusion of the UPC symbol in the label artwork of the item to be distributed by the manufacturer.
Start/stop character: Distinct characters used at the beginning and end of each bar code symbol that provides initial timing references and indicates the direction of scanning.
Substitution error: A misread of a bar code which results in another character being substituted for the correct character.
Starburst/sunburst: A type of circular scanning pattern used by some moving beam scanners. The pattern is designed so that, regardless of the orientation of the bar code symbol, at least one scan will pass completely through the symbol.
Symbol: A symbol is something that represents something else by association, resemblance, or convention. A bar code symbol is the bars and spaces that make up the bar code and excludes the media that it is printed on.
Symbology: Representation or expression by means of a symbol. A barcode symbology is a class of bar code. For example, Code 39 is a symbology as is UPC.
Telepen: A continuous code that encodes the full ASCII character set of 128 characters. Each alphanumeric character is represented by 16 modules and two bar widths.
Thermal printer: A thermal printer uses special, chemically treated label stock that changes colors when heated. The printer uses a set of pins which are electrically heated and in contact with the label stock. As the stock is moved over the pins and the pins are selectively heated, the chemical turns dark and the bar code is formed. Sometimes called direct thermal printer.
Thermal transfer printer: A thermal transfer printer is similar to a thermal printer, But a thermal transfer printer use a thin film or paper-based ribbon impregnated with a waxy coating. The pins melt the wax coating and the pigment in the coating is flowed onto the paper.
Uniform Code Council (UCC or UPCC): The organization in the USA responsible for overseeing and administering the Universal Product Code (UPC) in retail consumer industry.
Universal Product Code (UPC): Most commonly a 12-digit bar code pattern adopted by the U.S. grocery industry, which identifies the number system character (type of encoded product), five-digit manufacturer number assigned by the UCC, five-digit product code assigned by the manufacturer, and a modulo 10 check digit as the 12th character. The code is numeric, and there are other versions. Version E accommodates six digits, and Version D is a 12 + n-digit version.
UPC version A: UPC version A is the basic version of UPC and is usually the version seen on grocery store items in the United States. The symbology is used to encode the ten-digit Universal Product Code. An eleventh digit indicates the type of product, and a twelfth digit is a modulo check digit.
UPC version C: UPC version C is a special version of UPC used for industrial uses. The code is 12-digits long with a product type digit and a modulo check sum digit.
UPC version E: UPC version E is the next most common version of UPC. It is a zero suppression version of UPC. It is intended to be used on packaging which would be otherwise too small to use one of the other versions.
variable length code: A code that can be of any length within a range of lengths. The length of the bar code only depends on the data encoded.
video reader: a photo-optical device in the form of a linear array of video tube used to decode a bar code without contact and without any relative motion between the bar code and the reader.
VLD: Visible Laser Diode. A semiconductor laser which produces light between 670 and 680 nanometers, which is within the visible light spectrum.
void: The absence of ink within printed bars; can cause a bar to scan as a space.
wand reader: A hand-held scanning device used as a contact bar code reader. The wand resembles a large pen.
wedge/wedge reader: A bar code reader designed to fit in-line between a keyboard and a computer or CRT. The keyboard is plugged into the wedge and a cable from the wedge is plugged into the keyboard interface on the computer or CRT. Data scanned using a wedge appears as if the data was typed into the computer of CRT, eliminating the need to modify application software.
X dimension: The dimension of the narrowest element of a bar code symbol; wider elements are generally referred to as multiples of the X dimension. X dimension is usually stated in .001 inches. A 7.5 mil x dimension is .0075 inches.

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